Hook, a senior policy adviser to U.S. Secretary of State Mike Pompeo, spoke with Falih a day before the Organization of the Petroleum Exporting Countries gathers in Vienna to debate oil production cuts.

A Saudi Energy Ministry spokesman said of the talks between Falih and Hook: “We categorically deny such a meeting took place.” The sources maintained that the two men had held talks.

“OPEC is an independent organisation and is not part of the U.S. Department of Energy to take orders from Washington,” SHANA quoted Zanganeh as saying.

U.S. President Donald Trump has urged Saudi Arabia to refrain from output cuts in order to keep oil prices low. He said higher oil supplies were a payback from Riyadh for U.S. support for Saudi Arabia against arch-rival Iran.

The United States reimposed sanctions on Tehran last month. The measure has severely reduced Iranian oil flows and Washington has said it wants ultimately to drive Iranian shipments down to zero. (Reporting by Rania El Gamal; writing and editing by Dmitry Zhdannikov and Dale Hudson)